Date Reminder - Date Reminder reminds you of recurring or nonrecurring events, like birthdays, bills to pay...
Reminder Commander - Reminder manager that reminds you about important events in advance.
GoGetter - GoGetter is a task management system based on David Allen’s ever so popular Getting Things Done...
todoMini - Your web based TODO list.
Desktop-Reminder - Desktop-Reminder is a freeware task planner for Windows to manage your tasks and other to-dos’ in really easy way.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.